Autoimmunity is likely the result of a failed engagement of cells or factors that regulate the activity of immune cells directed against self tissues. Decades of research has uncovered multiple mechanisms of immune regulation, including cytokine deviation of the pathogenic response and active inhibition of pathogenic cells by TcR-peptide specific regulatory T cells. The discovery of these and other mechanisms makes the understanding of time at which various regulatory effects are initiated of great importance to design of effective therapies. Further, much of our understanding about the cells and their specificities involved with autoimmune regulation was derived from experimental models with well understood initiating antigenic targets. This proposal seeks to analyze and precisely quantitate the T cell populations that infiltrate the lesions of the experimental allergic encephalomyelitis (EAE) model of multiple sclerosis, by measurement of a huge array of the T cell antigen receptors (TcR) over the course of disease, a so-called immunoscope analysis. In addition, the phenotype of these cells will be simultaneously determined by a combination of surface receptor based sorting (FACS) and immunomodulatory cytokine expression measurement (RT-PCR using fluorescent measurement). Using prior knowledge of an understood phenotype of pathogenic and then regulatory cells, this proposal will "map" the time at which disease causing and disease limiting populations emerge within autoinflammatory lesions and peripheral lymphoid sites. Using the EAE system as a prototype system of autoimmune disease pathogenesis and regulation, a spontaneous model of IDDM, the NOD mouse, will be analyzed using an identical Immunoscope approach. Unlike the EAE model in B10.PL mice in which EAE is resolved through the activity of regulatory populations, NOD mice do not spontaneous regulate pathogenic cells sufficiently to prevent IDDM. Here, the emergence pattern of IDDM-causing T cells of suspected phenotypes will be mapped, and compared to the "time"/disease phase that one would expect regulatory populations to exert their protective effects. Comprehensive phenotyping of cells in the lesion of NOD mice may indicate the presence of ineffective regulatory cells, or the complete lack thereof. As pinnacle studies, underrepresented or unstimulated regulatory cells will be targeted for amplification as a therapy for IDDM.